Not sure if you have already traveled to China or not but be careful using google maps in China.
Since google services are blocked for the majority of people there, maps is not as up to date or as accurate as we are used to in the US. I saw this when I visited last spring.
On my iphone I found that Apple maps even has a special version that is only available in China. Using the Chinese version,China is very detailed but the rest of the world lacked a lot of detail (As I zoomed in to Wisconsin, satellite view disappeared before the state even filled the screen). As soon as I connected to a VPN, I was back on the version I was used to in the US and the China map lacked detail.
I'm not sure what the best maps solution is for Android in China but I would recommend searching Google a bit before you go. (oh, the irony )

My 7 showed up today. I had it running google maps for about a 2 hour drive and it seemed to stay connected to LTE much better throughout the trip than my 6 did previously. My 6 would often get stuck on 1x and 3G whenever it was actively trying to load data (constantly loading the map as I am driving). Not sure if this is due to the new phone, new carrier update with iOS 10 or both.

I got a tracking number on Sunday night for 2 of the 4 phones that I ordered even though I expected all 4 to ship together (all 4 were supposed to ship prior to 9/16)
Currently UPS doesn't show any info on the tracking number Sprint listed.

A little follow up now that I am back home:
After first landing in Mexico, my phone would not register on any network automatically so I had to manually go in to iOS settings>carrier, unslect "automatically select carrier", and select Movistar. After doing this the first time for my phone and my wife's, the phones automarically connected with Movistar on their own for the rest of the trip. iOS seems to have a feature built in called "Dail assist" which popped up each time I made a phone call (none of my contacts have a +1 in front of the saved number - I think Dial assist helped with this)
iMessages and incoming SMS worked flawlessly(including short codes) but outgoing SMS/MMS needed a 1 added in front of the number you were sending the message to (which was a bit of a pain because the incoming message did not show a 1 prior to the number so a simple reply did not work).
Upon returning to the states, no changes were required to the iPhones, both found Sprint right away and we haven't had issues like others have mentioned.
One thing Sprint should improve is how they show your current usage on MySprint. I have also seen others mention this so I am not concerned but it shows that I have used 49/0 International Roaming minutes. The data & text categories both recognize that I am on Sprint OpenWorld so I would think the voice category would also be able to be programmed to do that.
Overall it was a very good experience (and you can't beat free!) Thanks Sprint!
Edit: Spelling...

I know this is all new and speculation at this point, but if this is the case I could see this being a big issue for sprint. The general user won't know the difference between native coverage and LTE roaming, will use the entire roaming allotment and then wonder why their Sprint LTE connection is no longer working...